Glyphosate

[Blagoje]

I have to determine content of glyphosate in formulations (no postcolumn, no residua). Is possible to do it using UV detector? Can you recommend me a column for the determination?

Many thanks to all!

[rhaefe]

We are testing our glyphosate columns (PRP-X400) using an RI detector. Concentration of glyphosate and aminomethylphosphonic acid in our test samples is high. For UV detection prior derivatization might be required.
Probably some Pickering (or ex-Pickering, hello Mark!) can answer this question.

[H.Thomas]

Glyphosate has no chromophore -> no UV-detection.

Commonly used is FMOC-derivatisation (precolumn), separation on standard C18 column and fluorescence detection. UV might work here if concs are high.

[Mark Tracy]

The post-column technique is nice for residue determination (EPA 547), but it is not really a good idea for formulation work. I would probably take Robert's advice.

[Blagoje]

To Mark:

To take RI detection on Hamilton column? Is it possible to avoid RI detection and any other except UV? At the moment our budget restrict any purchase and we have UV and PDA detectors only.

For example, is it possible to use '- peaks'? To add a strong absorptive compound to the mobile phase and glyphosate will give negative peaks?!

To Robert:

Is it possible to determine glyphosate on both 79398 and 79473 columns?

Thanks to all!

[Russ]

There was an AOAC method for glyphosate using a UV detector in the 15th edition of AOAC methods. They used 195 nm. I think I have another published method using a UV detector but it is at home. Like you, we do not have an RI or post-column derivatization capability so we use a UV detector. We use 205 nm as it seemed less noisy (though the signal-to-noise determination was done by semi-calibrated eyeball). It is hardly ideal, but has been useable.

[rhaefe]

Blagoje

yes, both columns can be used for glyphosate analysis. The only difference is column id (2.1 and 4.1mm id, respectively)

[Fabiano]

I also used 205 nm for quantitation, during synthesis work. Whatman Partisil column with 20mM phosfate buffer.

Fabiano

[Markus Laeubli, Metrohm]

We determined glyphosate with conductivity detection on the Metrosep A Supp 3 - 250 column (6.1005.320). Using a barbonate/bicarbonate eluent.

[bigdaf]

Glyphosate can also be determined using a Hypercarb (porous graphitic carbon) HPLC column from Thermo Scientific.